Knife sharpener



FIG. 1 is a one end perspective view of the knife sharpener showing a first embodiment of my new design;

FIG. 2 is a top plan view thereof, the bottom being plain and unornamented;

FIG. 3 is a side elevational view thereof, the opposite side being a mirror image;

FIG. 4 is an opposite end elevational view thereof;

FIG. 5 is a one end perspective view of a knife sharpener showing a second embodiment of my new design;

FIG. 6 is a reduced top plan view thereof, the bottom being plain and unornamented;

FIG. 7 is a reduced side elevational view thereof, the opposite side being a mirror image;

FIG. 8 is a reduced opposite end elevational view thereof. 

The ornamental design for a knife sharpener, as shown and described. 